Iron Threshold In Organic Fertilizer That Potentially Cause Iron Toxicity At Wetland Rice

Abstract

Many scientists reported that intensive agricultural using a high rate of in anorganic NPK fertilizer and pesticide, caused declining in soil productivity, soil degradation, and increased environmental pollution. Organic content of these soils are mostly very low, while it is widely know that organic matter is very important to keep physical, chemical, and biological properties of soil as well as soil productivity. However, the quality and quantity of organic matter to be used are important factor determining the impact on the soil. In Ministry of Agriculture Decree (Permentan) No. 28, 2009, a maximum limit of total iron content in organic fertilizer is 8.000 mg kg-1 while most of the current organic fertilizers available in the market exceed this limit. The objectives of the study were to know the quality of organic fertilizer currently available in the market in Java Island and to determine the threshold level of iron that potentially cause iron toxicity in rice. The survey was conducted on May to July 2011 in java Island for survey and collecting a number of organic fertilizer currently marketed and the pot experiment was conducted on May to November 2011 in green house. This experiment using a randomized complete block design with two factors; the types of soil (Endoaquert, Tropaquept, and Hapludult) and organic fertilizer enriched with Fe (FeCl3) in various level. Each treatment was replicated three times. Survey results from 60 samples of granule organic fertilizer taken from several areas in Java Island with 11 parameters, there was indicated two samples (3 % from the total samples) that fulfilled several criteria following of Permentan No. 28, 2009 and no sample (0%) that fulfilled several criteria following of Permentan No. 70, 2011. The pot experiment results showed that the threshold of total iron content in granule organic fertilizer potentially cause iron toxicity for Endoaquert, Tropaquept, and Hapludult were 62.900, 37.300, and 61.100 mg kg-1 respectively. The threshold of total iron content in granule organic fertilizer potentially cause iron toxicity in rice of IR 64 variety with dose 1 ton/ha is 59.500 mg kg-1.